Shareholders' Equity (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Jan. 01, 2017
Shareholders' equity activity [Roll Forward]          
Balance at beginning of period     $ 9,448 $ 15,495  
Effect of early adoption of income tax consequences of intra-entity transfer of assets other than inventory $ (384) [1]   (384) [1]   $ (384)
Payments of dividends to shareholders     (469) (465)  
Stock plans     340 348  
Other     (52) (39)  
Comprehensive income (loss) 363 $ 8 363 (5,613)  
Balance at end of period 9,246 9,726 9,246 9,726  
Company shareholders' equity          
Shareholders' equity activity [Roll Forward]          
Balance at beginning of period     9,409 15,462  
Effect of early adoption of income tax consequences of intra-entity transfer of assets other than inventory [1] (384)   (384)    
Payments of dividends to shareholders     (469) (465)  
Stock plans     340 348  
Other     (46) (52)  
Comprehensive income (loss)     367 (5,611)  
Balance at end of period 9,217 9,682 9,217 9,682  
Noncontrolling interest in consolidated subsidiaries          
Shareholders' equity activity [Roll Forward]          
Balance at beginning of period     39 33  
Effect of early adoption of income tax consequences of intra-entity transfer of assets other than inventory [1] 0   0    
Payments of dividends to shareholders     0 0  
Stock plans     0 0  
Other     (6) 13  
Comprehensive income (loss)     (4) (2)  
Balance at end of period $ 29 $ 44 $ 29 $ 44  
[1] Represents a cumulative-effect adjustment to retained earnings upon our adoption of a new accounting standards update on the income tax consequences of intra-entity transfers of assets other than inventory which was effective January 1, 2017. See Note 8 for further information.